The present invention relates to the field of paper manufacturing. More particularly, the present invention relates to the manufacture of absorbent tissue products such as bath tissue, facial tissue, napkins, towels, wipers, and the like. Specifically, the present invention relates to improved fabrics used to manufacture absorbent tissue products having visually discernible background texture regions bordered by curvilinear decorative elements, methods of tissue manufacture, methods of fabric manufacture, and the actual tissue products produced.
In the manufacture of tissue products, particularly absorbent tissue products, there is a continuing need to improve the physical properties and final product appearance. It is generally known in the manufacture of tissue products that there is an opportunity to mold a partially dewatered cellulosic web on a papermaking fabric specifically designed to enhance the finished paper product""s physical properties. Such molding can be applied by fabrics in an uncreped through air dried process as disclosed in U.S. Pat. No. 5,672,248 issued on Sep. 30, 1997 to Wendt et al., or in a wet pressed tissue manufacturing process as disclosed U.S. Pat. No. 4,637,859 issued on Jan. 20, 1987 to Trokhan. Wet molding typically imparts desirable physical properties independent of whether the tissue web is subsequently creped, or an uncreped tissue product is produced.
However, absorbent tissue products are frequently embossed in a subsequent operation after their manufacture on the paper machine, while the dried tissue web has a low moisture content, to impart consumer preferred visually appealing textures or decorative lines. Thus, absorbent tissue products having both desirable physical properties and pleasing visual appearances often require two manufacturing steps on two separate machines. Hence, there is a need to combine the generation of visually discernable background texture regions bordered by curvilinear decorative elements with the paper manufacturing process to reduce manufacturing costs. There is also a need to develop a paper manufacturing process that not only imparts visually discernable background texture regions bordered by curvilinear decorative elements to the sheet, but also maximizes desirable physical properties of the absorbent tissue products without deleteriously affecting other desirable physical properties.
Previous attempts to combine the above needs, such as those disclosed in U.S. Pat. No. 4,967,805 issued on Nov. 6, 1990 to Chiu, U.S. Pat. No. 5,328,565 issued on Jul. 12, 1994 to Rasch et al., and in U.S. Pat. No. 5,820,730 issued on Oct. 13, 1998 to Phan et al., have manipulated the papermaking fabric""s drainage in different localized regions to produce a pattern in the wet tissue web in the forming section of the paper machine. Thus, the texture results from more fiber accumulation in areas of the fabric having high drainage and fewer fibers in areas of the fabric having low drainage. Such a method can produce a dried tissue web having a non-uniform basis weight in the localized areas or regions arranged in a systematic manner to form the texture. While such a method can produce textures, the sacrifice in the uniformity of the dried tissue web""s physical properties such as tear, burst, absorbency, and density can degrade the dried tissue web""s performance while in use.
For the foregoing reasons, there is a need to generate aesthetically pleasing combinations of background texture regions and curvilinear decorative elements in the dried or partially dried tissue web, while being manufactured on the paper machine, using a method that produces a substantially uniform density dried tissue web which has improved performance while in use.
Numerous woven fabric designs are known in papermaking. Examples are provided by Sabut Adanur in Paper Machine Clothing, Lancaster, Pa.: Technomic Publishing, 1997, pp. 33-113, 139-148, 159-168, and 211-229. Another example is provided in Patent Application WO 00/63489, entitled xe2x80x9cPaper Machine Clothing and Tissue Paper Produced with Same,xe2x80x9d by H. J. Lamb, published on Oct. 26, 2000.
The present invention comprises paper manufacturing processes that may satisfy one or more of the foregoing needs. For example, a paper manufacturing fabric of the present invention, when used as a throughdrying fabric in an uncreped tissue making process, produces an absorbent tissue product having a substantially uniform density as well as possessing visually discernable background texture regions bordered by curvilinear decorative elements. The present invention is also directed towards fabrics for manufacturing the absorbent tissue product, processes of making the absorbent tissue product, processes of making the fabric, and the absorbent tissue products themselves.
Therefore in one aspect, the present invention relates to a fabric for producing an absorbent tissue product with visually discernible background texture regions bordered by curvilinear decorative elements comprising: a woven fabric having background texture regions formed by MD warp floats alternating with MD warp sinkers woven into a support structure (i.e., at least a single layer of CD shutes) below the MD floats; the warps and shutes at the borders of the background texture regions are arrayed to form transition regions comprising the curvilinear decorative elements.
In another aspect, the present invention relates to a method for manufacturing an absorbent tissue product with visually discernable background texture regions bordered by curvilinear decorative elements comprising: forming the wet tissue web, partially dewatering the wet tissue web, rush transferring the wet tissue web, wet molding the wet tissue web into a fabric having visually discernible background texture regions bordered by curvilinear decorative elements, and throughdrying the web.
In an additional aspect, the present invention relates to a tissue product with background texture regions bordered by curvilinear decorative elements that form aesthetically pleasing repeating patterns comprising: visually discernable background texture regions of MD ripples, ridges, or the like, corresponding to a image of the background texture regions of the fabric, bordered by curvilinear decorative elements, corresponding to an image of the curvilinear transition regions of the fabric, where the curvilinear decorative elements in the tissue web are visually distinct from the background texture regions in the tissue.
Unlike U.S. Pat. No. 5,672,248 issued on Sep. 30, 1997 to Wendt et al., where the warp knuckles are closely spaced or contacting and arranged into patterns, the present invention produces the curvilinear decorative elements in the absorbent tissue product at a substantially continuous transition region which forms borders between background texture regions. The curvilinear decorative elements comprise geometric configurations with the leading end of one or more raised MD floats adjacent to or in proximity to the trailing end of another raised MD float. The decorative pattern consists of the visually discernable background texture regions, such as corrugations, lines, ripples, ridges, and the like, and the curvilinear decorative elements which form transition regions between the background texture regions. It is the arrangement of the transition regions in the present invention that provide the decorative pattern. Because the curvilinear decorative elements are produced at the transition region (rather than from a decorative pattern resulting from shoulder to shoulder or side by side positioning of warp knuckles of other fabrics) the raised MD floats can be purposely distributed more uniformly across the sheet side surface of the fabric to improve the uniformity and CD stretch properties of the tissue web with respect to physical properties while still imparting a distinctive texture highlighted by curvilinear decorative elements as a decorative pattern to the tissue web. In addition, because the curvilinear decorative elements producing the distinctive pattern occurs at the relatively small transition area, it is possible to weave the fabric with more intricate patterns than possible in the fabrics disclosed in U.S. Pat. No. 5,672,248.
The background texture regions are designed to impart preferred finished product properties when used as an UCTAD throughdrying fabric, including roll bulk, stack bulk, CD stretch, drape, and durability. The curvilinear decorative elements may provide additional hinge points to enhance finished product drape. The background texture regions in the finished product contrast visually with the curvilinear transition regions, providing the decorative effect.
In one aspect of the present invention, the curvilinear decorative elements form woven transition regions which allow the warps to alternate function between MD warp float and MD warp sinker. When finished so the warps are parallel to the MD, the background texture regions across each transition region are out of phase with each other, with the highest parts of one background texture region corresponding to the lowest part of the other. This out of phase alternation results in improved anti-nesting behavior, significantly improving the roll firmnessxe2x80x94roll bulk relationship at a given one-sheet caliper.
In some embodiments, all of the floats (or elevated regions) in a background region are surrounded by sinkers (or depressed regions), with the possible exception of floats adjacent to a transition region or fabric edge, and all of the sinkers (or depressed regions) in a background region are surrounded by floats (or elevated regions), with the possible exception of sinkers adjacent to a transition region or fabric edge.